import re
email_list=["xiaowang@163.com","xiaowang@1636com","xiaowang@163.comheihei",".com.xiaoming@qq.com"]
for email in email_list:
    ret=re.match(r'\w{5,20}@163\.com$',email)
    if ret:
        print(f'{email}是合法邮箱')
    else:
        print(f'{email}不是合法邮箱')